----------------------------------------------------
Exception at EIP=053d1e59 (ioport_port::read()+0x0009): ACCESS VIOLATION
While attempting to read memory at 00000004
-----------------------------------------------------
EAX=00000000 EBX=0028bc80 ECX=00000000 EDX=0028bbf0
ESI=00000036 EDI=00800140 EBP=0028bc48 ESP=0028bbc0
-----------------------------------------------------
Stack crawl:
  0028bc48: 053d1e59 (ioport_port::read()+0x0009)
  0028bc98: 00623103 (cps_state::cps1_cps_b_r(address_space&, unsigned int, unsi
gned short)+0x01a3)
  0028bcc8: 06e67725 (handler_entry_read_delegate<1, 0, 1, device_delegate<unsig
ned short (address_space&, unsigned int, unsigned short)> >::read(unsigned int,
unsigned short)+0x0035)
  0028bce8: 06f0d067 (handler_entry_read_dispatch<14, 1, 0, 1>::read(unsigned in
t, unsigned short)+0x0027)
  0028bd08: 070eb678 (handler_entry_read_dispatch<24, 1, 0, 1>::read(unsigned in
t, unsigned short)+0x0028)
  0028bd38: 06c1062a (address_space_specific<1, 0, (endianness_t)1>::read_word_u
naligned(unsigned int)+0x004a)
  0028bd58: 0530f6f4 (debugger_cpu::read_word(address_space&, unsigned int, bool
)+0x0054)
  0028bda8: 05325c71 (debug_view_memory::read(unsigned char, unsigned int, unsig
ned long long&)+0x01d1)
  0028bea8: 053291dc (debug_view_memory::view_update()+0x06ac)
  0028bef8: 0531cc7f (debug_view::set_visible_position(debug_view_xy)+0x008f)
  0028bf88: 03796788 (debugview_info::static_view_proc(HWND__*, unsigned int, un
signed int, long)@16+0x0218)
  0028bfb4: 761b62fa (gapfnScSendMessage+0x0332)
  0028c02c: 761b6d3a (GetThreadDesktop+0x00d7)
  0028c070: 761b965e (GetWindow+0x03f0)
  0028c094: 761b96c5 (SendMessageW+0x004c)
  0028c0b4: 0379557d (debugview_info::send_pagedown()+0x002d)
  0028c344: 0379cda0 (editwin_info::edit_proc(unsigned int, unsigned int, long)+
0x0370)
  0028c364: 0379d338 (editwin_info::static_edit_proc(HWND__*, unsigned int, unsi
gned int, long)@16+0x0038)
  0028c390: 761b62fa (gapfnScSendMessage+0x0332)
  0028c408: 761b6d3a (GetThreadDesktop+0x00d7)
  0028c468: 761b77c4 (CharPrevW+0x0138)
  0028c478: 761b788a (DispatchMessageW+0x000f)
  0028c498: 0377b385 (winwindow_dispatch_message(running_machine&, tagMSG*)+0x00
25)
  0028c4e8: 0378f24f (debugger_windows::wait_for_debugger(device_t&, bool)+0x019
f)
  0028c508: 0376c54f (osd_common_t::wait_for_debugger(device_t&, bool)+0x001f)
  0028c598: 0531bb2e (device_debug::instruction_hook(unsigned int)+0x033e)
  0028c628: 0434f1e1 (m68000_base_device::execute_run()+0x0851)
  0028c6a8: 0543995c (device_scheduler::timeslice()+0x03fc)
  0028c728: 053f28c7 (running_machine::run(bool)+0x0117)
  0028f6d8: 03818666 (mame_machine_manager::execute()+0x01e6)
  0028f868: 03887683 (cli_frontend::start_execution(mame_machine_manager*, std::
vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<c
har> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>,
std::allocator<char> > > > const&)+0x0453)
  0028faa8: 03887cd9 (cli_frontend::execute(std::vector<std::__cxx11::basic_stri
ng<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__c
xx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >&)+0x
0039)
  0028fad8: 0381640d (emulator_info::start_frontend(emu_options&, osd_interface&
, std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allo
cator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<
char>, std::allocator<char> > > >&)+0x002d)
  0028fed8: 09bd936a (main+0x01aa)
  0028ff78: 0040138b (__tmainCRTStartup+0x023b)
  0028ff94: 74ff344d (BaseThreadInitThunk+0x0012)
  0028ffd4: 777a9802 (RtlInitializeExceptionChain+0x0063)
  0028ffec: 777a97d5 (RtlInitializeExceptionChain+0x0036)